However, in the nearly five years since the first article describing the development of stem cells derived from adult cells — so-called induced pluripotent stem cells (iPSCs) — unique problems inherent in their use have surfaced and even their immunological safety has been called into question.
According to Paul S. Knoepfler, UC Davis associate professor of cell biology and human anatomy, finding such obstacles in such a new and novel approach is not surprising and should not dissuade investigators from actively pursuing this avenue of research. Their perspective, "Inducing iPSCs to escape the dish," suggests research strategies to advance the field more rapidly toward applications for human diseases.
iPSCs were first produced in 2006 from mouse cells and in 2007 from human cells. They have many of the same regenerative properties as human embryonic stem cells, but they are derived in a lab from adult cells, such as skin cells, by inducing or forcing them to express specific genes that are normally dormant in that type of cell. In theory, a person's skin cells could be induced to make neurons that produce the neurotransmitter dopamine, for example, and be delivered to brain regions where it is lacking in patients with Parkinson's disease. Similarly, cells could be induced to regenerate heart muscle and blood vessels after a heart attack, or neurons following a spinal cord injury. Many labs at UC Davis, including the Knoepfler lab, are producing and studying human iPSCs.
One advantage cited for iPSCs over stem cells derived from embryos is that problems of rejection due to immunological differences between the donor (the embryo) and the patient would be eliminated, because the iPSCs would be derived from each individual patient. A recent study using iPSCs in mice found that tissue rejection may, in fact, occur in some cases. Another concern with using either iPSCs or embryonic stem cells is that cells with the ability to turn into many different cell types may grow out of control, producing cancerous tumors.
MEDICA.de; Source: University of California - Davis Health System